Expansion valve control system and method for air conditioning apparatus
First Claim
1. A method of controlling an expansion valve of a residential HVAC system, comprising:
- in response to at least one of a call for cooling and a call for heating, controlling the expansion valve to achieve a first predetermined position, wherein the controlling is achieved without respect to a superheat of the HVAC system occurring substantially contemporaneously with the controlling;
wherein the first predetermined position is a predetermined percentage greater than a previous position of the expansion valve achieved (1) during operation of the expansion valve in response to at least one of a previous call for cooling and a previous call for heating and (2) during control of the expansion valve as a function of the superheat of the HVAC system occurring substantially contemporaneously with the at least one of the previous call for cooling and the previous call for heating, and wherein the predetermined percentage is the product of multiplying a substantially constant multiplying factor against the previous position of the expansion valve; and
after achieving the first predetermined position, controlling the expansion valve according to a weighted function that increasingly depends upon a function of a substantially contemporaneous superheat of the HVAC system.
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Accused Products
Abstract
A vapor compression air conditioning system includes a motor operated expansion valve and control unit including sensors for determining the amount of superheat of the working fluid at or adjacent to the compressor inlet. Expansion valve position is adjusted to maintain a predetermined amount of superheat. The sensors may sense working fluid evaporator temperature and temperature downstream of the evaporator. Dual motor operated expansion valves may be disposed in the working fluid conduit between the heat exchangers in a reversible system. In operation, the expansion valve position may be set as a function of ambient temperature, a previous position, and predetermined superheat requirements to minimize liquid ingestion by the compressor.
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Citations
24 Claims
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1. A method of controlling an expansion valve of a residential HVAC system, comprising:
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in response to at least one of a call for cooling and a call for heating, controlling the expansion valve to achieve a first predetermined position, wherein the controlling is achieved without respect to a superheat of the HVAC system occurring substantially contemporaneously with the controlling; wherein the first predetermined position is a predetermined percentage greater than a previous position of the expansion valve achieved (1) during operation of the expansion valve in response to at least one of a previous call for cooling and a previous call for heating and (2) during control of the expansion valve as a function of the superheat of the HVAC system occurring substantially contemporaneously with the at least one of the previous call for cooling and the previous call for heating, and wherein the predetermined percentage is the product of multiplying a substantially constant multiplying factor against the previous position of the expansion valve; and after achieving the first predetermined position, controlling the expansion valve according to a weighted function that increasingly depends upon a function of a substantially contemporaneous superheat of the HVAC system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of controlling an expansion valve of a residential HVAC system, comprising:
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providing an open loop profile for controlling the expansion valve without feedback related to a superheat of the HVAC system, wherein the open loop profile comprises multiplying a substantially constant multiplying factor that is not dependent upon any previous positions of the expansion valve against a previous position of the expansion valve; providing a feedback control algorithm for controlling, to the exclusion of the open loop profile, the expansion valve as a function of at least one of a substantially contemporaneously measured temperature of the HVAC system and a substantially contemporaneously measured pressure of the HVAC system; and operating the expansion valve in response to at least one of a call for cooling and a call for heating, the operating comprising; controlling the expansion valve according to the open loop profile; controlling the expansion valve as a weighted function of both the open loop profile and the feedback control algorithm; and controlling the expansion valve according to the feedback control algorithm. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method of controlling an expansion valve of a residential HVAC system, comprising:
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in response to a first call operation of the HVAC system to meet a first call temperature demand, at least partially controlling the expansion valve in response to at least one of (1) a first call temperature that is related to a first call superheat of the HVAC system and (2) a first call pressure that is related to the first call superheat, the at least one of the first call temperature and the first call pressure occurring during operation of the HVAC system to meet the first call temperature demand; discontinuing the first call operation; in response to a subsequent call operation of the HVAC system to meet a subsequent call temperature demand, controlling the expansion valve according to an open loop profile for a first subsequent period in which a subsequent call superheat is substantially ignored, wherein the open loop profile comprises multiplying a substantially constant multiplying factor that is not dependent upon any previous positions of the expansion valve against a previous position of the expansion valve; and after the first subsequent period, controlling the expansion valve for a second subsequent period according to a weighted function of both (1) the open loop profile and (2) a feedback control algorithm in which the subsequent call superheat is not substantially ignored. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification